In laundering it is common to treat various types of fabrics such as wool, cotton, silk, nylon, polyester, permanent-press, and the like with chemicals which are fabric-conditioning or treating agents to render the fabrics soft to the touch, to reduce tangling, knotting or wrinkling, to render them free of static electricity, to render them bacteria-resistant, to deodorize them, and to otherwise condition them. The use of fabric conditioners permits dried clothes to be sorted and folded more easily and quickly. These results are ordinarily achieved by introducing an aqueous solution or dispersion of the fabric-conditioning agent into the wash water during the washing cycle of the laundry process or by introducing such an aqueous solution or dispersion of fabric-conditioning agent into the rinse water during the rinsing cycle of the laundry process. Experience has shown that addition of the fabric-conditioning agents during the rinse cycle of the laundry process is often significantly more effective than addition of the fabric-conditioning agents during the wash cycle. Since some clothes washing machines do not have automatic fabric softener dispensers, a homemaker must be present during the washing of fabrics to manually add the fabric conditioner during the rinse cycle. This is inconvenient and, consequently, is often forgotten. Even when the washing machine is equipped with an automatic dispenser, the use of a fabric-conditioner is still a messy operation requiring measuring of a liquid suspension, is wasteful and is ecologically undesirable because a significant amount of the fabric conditioner is lost to the drain. Moreover, the fabric softener is usually added to the deep rinse where some soap or detergent and soil may still be present, leading to redeposition problems and interaction between the anionic detergent and cationic softeners (which are mutually incompatible), with subsequent loss of efficiency.
As a result of combinations of the above factors, a survey has shown that many homemakers use fabric softeners irregularly and on the basis of "when I remember" or "when it is needed" with equally irregular performance as regards antistatic and other fabric conditioning properties.
The use of liquid fabric conditioning agents in machine dryers has been suggested in the past, but the idea has not gained widespread commercial acceptance probably as a result of such factors as the need for complex dispensing equipment.
Recently, means and techniques have been developed for dispensing solid fabric conditioners in a machine laundry dryer. Flexible substrates coated or impregnated with a fabric softening and/or anti-static agent and designed for use in clothes dryers are now commercially available. These commercial articles are pre-measured, disposable, single-use sheets and can be expensive to use. Perhaps the most severe difficulty with these coated or impregnated substrates has been the danger that they may mark or stain the clothes in the dryer. One route for overcoming this difficulty is to coat the flexible substrate with a solid chemical agent which remains solid throughout the operating temperature range of the dryer (e.g. throughout the range of 50.degree.-90.degree. C.). The flexing of the flexible substrate which accompanies the clothes tumbling action of a dryer drum is presently believed to cause the coating of the chemical agent to develop a flaking action, resulting in the transfer of the agent to the clothes in the form of tiny solid flakes or crystals. These flakes of the solid agent are apparently considered less likely to cause staining as compared to an agent which is molten or significantly softened within the 50.degree.-90.degree. C. range. This coated flexible substrate approach is believed to be best suited for single-use flexible sheets which are separated out from the dryer load after the drying cycle and then discarded.